The CHILL language is similar in size and complexity to the Ada language. The first specification of the CHILL language was published in 1980, a few years before Ada. CHILL is unusual in that it supports two forms of declaration syntax, one based on Cobol and the other on PL/1.

ITU provides a standard CHILL compiler.
A free CHILL compiler was bundled with GCC up to version 2.95, however, was removed from later versions. An object-oriented version, called Object CHILL, was developed as well.[1]

ITU is responsible for the CHILL standard, known as ITU-T Rec. Z.200. The equivalent ISO standard is ISO/IEC 9496:2003. (The text of the two documents is the same). In late 1999 C.C.I.T.T. stopped maintaining the Chill standard.